I want to send a fast trigger pulse a short distance inside a
rackmount enclosure, a foot or two between boards. Signals will be
pretty fast differential PECL, maybe 120 ps edges.

The usual ribbon cable config would be

g g P N g g (maybe 120 ohms diff impedance)

namely a differential pair with surrounding grounds.

But one could also do

g g P g N g g or
g g P g g N g g (about 80 ohms per wire, 160 diff)

or even

g g P P g g N N g g (who knows?)

Maybe some would have lower losses than the first one.

Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
Lemo/Fisher connectors are too expensive and fussy.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

søndag den 23. maj 2021 kl. 02.36.56 UTC+2 skrev jla...@highlandsniptechnology.com:
> I want to send a fast trigger pulse a short distance inside a
> rackmount enclosure, a foot or two between boards. Signals will be
> pretty fast differential PECL, maybe 120 ps edges.
>
> The usual ribbon cable config would be
>
> g g P N g g (maybe 120 ohms diff impedance)
>
> namely a differential pair with surrounding grounds.
>
> But one could also do
>
> g g P g N g g or
> g g P g g N g g (about 80 ohms per wire, 160 diff)
>
> or even
>
> g g P P g g N N g g (who knows?)
>
>
> Maybe some would have lower losses than the first one.
>
> Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
> Lemo/Fisher connectors are too expensive and fussy.
>

how about a SATA cable? I've also seen several PCIe extenders
using a USB3 cable and connectors

both are two pairs and grounds that should be good for several Ghz

On Sat, 22 May 2021 17:51:14 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

>søndag den 23. maj 2021 kl. 02.36.56 UTC+2 skrev jla...@highlandsniptechnology.com:
>> I want to send a fast trigger pulse a short distance inside a
>> rackmount enclosure, a foot or two between boards. Signals will be
>> pretty fast differential PECL, maybe 120 ps edges.
>>
>> The usual ribbon cable config would be
>>
>> g g P N g g (maybe 120 ohms diff impedance)
>>
>> namely a differential pair with surrounding grounds.
>>
>> But one could also do
>>
>> g g P g N g g or
>> g g P g g N g g (about 80 ohms per wire, 160 diff)
>>
>> or even
>>
>> g g P P g g N N g g (who knows?)
>>
>>
>> Maybe some would have lower losses than the first one.
>>
>> Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
>> Lemo/Fisher connectors are too expensive and fussy.
>>
>
>how about a SATA cable? I've also seen several PCIe extenders
>using a USB3 cable and connectors
>
>both are two pairs and grounds that should be good for several Ghz
>
>
>

We could use a usb C connector on each board and a short cable. But
the C-to-C cables seem to be charging cables, probably not good for
fast signals.

USB data cables rarely have the same connector on both ends. Never?

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

søndag den 23. maj 2021 kl. 03.06.27 UTC+2 skrev jla...@highlandsniptechnology.com:
> On Sat, 22 May 2021 17:51:14 -0700 (PDT), Lasse Langwadt Christensen
> <lang...@fonz.dk> wrote:
>
> >søndag den 23. maj 2021 kl. 02.36.56 UTC+2 skrev jla...@highlandsniptechnology.com:
> >> I want to send a fast trigger pulse a short distance inside a
> >> rackmount enclosure, a foot or two between boards. Signals will be
> >> pretty fast differential PECL, maybe 120 ps edges.
> >>
> >> The usual ribbon cable config would be
> >>
> >> g g P N g g (maybe 120 ohms diff impedance)
> >>
> >> namely a differential pair with surrounding grounds.
> >>
> >> But one could also do
> >>
> >> g g P g N g g or
> >> g g P g g N g g (about 80 ohms per wire, 160 diff)
> >>
> >> or even
> >>
> >> g g P P g g N N g g (who knows?)
> >>
> >>
> >> Maybe some would have lower losses than the first one.
> >>
> >> Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
> >> Lemo/Fisher connectors are too expensive and fussy.
> >>
> >
> >how about a SATA cable? I've also seen several PCIe extenders
> >using a USB3 cable and connectors
> >
> >both are two pairs and grounds that should be good for several Ghz
> >
> >
> >
> We could use a usb C connector on each board and a short cable. But
> the C-to-C cables seem to be charging cables, probably not good for
> fast signals.
>
> USB data cables rarely have the same connector on both ends. Never?

seems like USB3 is quite common with USB-A at both ends, that's also
the ones I've seen used for PCIe extenders

https://www.amazon.com/UGREEN-Transfer-Enclosures-Printers-Cameras/dp/B00P0E3954

On 2021-05-23, jlarkin@highlandsniptechnology.com <jlarkin@highlandsniptechnology.com> wrote:
>
>
> I want to send a fast trigger pulse a short distance inside a
> rackmount enclosure, a foot or two between boards. Signals will be
> pretty fast differential PECL, maybe 120 ps edges.
>
> The usual ribbon cable config would be
>
> g g P N g g (maybe 120 ohms diff impedance)
>
> namely a differential pair with surrounding grounds.
>
> But one could also do
>
> g g P g N g g or
> g g P g g N g g (about 80 ohms per wire, 160 diff)
>
> or even
>
> g g P P g g N N g g (who knows?)
>
>
> Maybe some would have lower losses than the first one.
>
> Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
> Lemo/Fisher connectors are too expensive and fussy.

perhaps SATA or ESATA data cable.

It's got a spare lane that you don't need but it's commodity PC
hardware, so competitively priced and should work better than an unshielded ribbon.

--
Jasen.

On Sun, 23 May 2021 04:48:48 -0000 (UTC), Jasen Betts
<usenet@revmaps.no-ip.org> wrote:

>On 2021-05-23, jlarkin@highlandsniptechnology.com <jlarkin@highlandsniptechnology.com> wrote:
>>
>>
>> I want to send a fast trigger pulse a short distance inside a
>> rackmount enclosure, a foot or two between boards. Signals will be
>> pretty fast differential PECL, maybe 120 ps edges.
>>
>> The usual ribbon cable config would be
>>
>> g g P N g g (maybe 120 ohms diff impedance)
>>
>> namely a differential pair with surrounding grounds.
>>
>> But one could also do
>>
>> g g P g N g g or
>> g g P g g N g g (about 80 ohms per wire, 160 diff)
>>
>> or even
>>
>> g g P P g g N N g g (who knows?)
>>
>>
>> Maybe some would have lower losses than the first one.
>>
>> Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
>> Lemo/Fisher connectors are too expensive and fussy.
>
>perhaps SATA or ESATA data cable.
>
>It's got a spare lane that you don't need but it's commodity PC
>hardware, so competitively priced and should work better than an unshielded ribbon.

That's interesting. I wonder if regular ENIG plating is good enough
for the pcb fingers.

I haven't done a card-edge connection in decades.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On 2021-05-23, jlarkin@highlandsniptechnology.com <jlarkin@highlandsniptechnology.com> wrote:
>
> That's interesting. I wonder if regular ENIG plating is good enough
> for the pcb fingers.
>
> I haven't done a card-edge connection in decades.

Usually manufactured sockets are used, but yeah the springs are in the
plug, so it could work with an edge connector.

eg: socket drawing
https://media.digikey.com/pdf/Data%20Sheets/Molex%20PDFs/6780050xx_Dwg.pdf

--
Jasen.

On Sunday, 23 May 2021 at 06:14:30 UTC+1, jla...@highlandsniptechnology.com wrote:
> On Sun, 23 May 2021 04:48:48 -0000 (UTC), Jasen Betts
> <use...@revmaps.no-ip.org> wrote:
>
> >On 2021-05-23, jla...@highlandsniptechnology.com <jla...@highlandsniptechnology.com> wrote:
> >>
> >>
> >> I want to send a fast trigger pulse a short distance inside a
> >> rackmount enclosure, a foot or two between boards. Signals will be
> >> pretty fast differential PECL, maybe 120 ps edges.
> >>
> >> The usual ribbon cable config would be
> >>
> >> g g P N g g (maybe 120 ohms diff impedance)
> >>
> >> namely a differential pair with surrounding grounds.
> >>
> >> But one could also do
> >>
> >> g g P g N g g or
> >> g g P g g N g g (about 80 ohms per wire, 160 diff)
> >>
> >> or even
> >>
> >> g g P P g g N N g g (who knows?)
> >>
> >>
> >> Maybe some would have lower losses than the first one.
> >>
> >> Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
> >> Lemo/Fisher connectors are too expensive and fussy.
> >
> >perhaps SATA or ESATA data cable.
> >
> >It's got a spare lane that you don't need but it's commodity PC
> >hardware, so competitively priced and should work better than an unshielded ribbon.
> That's interesting. I wonder if regular ENIG plating is good enough
> for the pcb fingers.
>
> I haven't done a card-edge connection in decades.
> --

https://www.amazon.com/Anker-Powerline-Delivery-Matebook-Chromebook/dp/B072JYDQ7N

This should do what you want: Anker Powerline II USB-C to USB-C 3.1 Gen 2 Cable (3ft)

John

On Sun, 23 May 2021 10:33:24 -0700 (PDT), "ke...@kjwdesigns.com"
<keith@kjwdesigns.com> wrote:

>On Saturday, 22 May 2021 at 17:36:56 UTC-7, jla...@highlandsniptechnology.com wrote:
>...
>
>We often use Samtec connectors and cables for similar applications.
>
>For high bandwidth with excellent signal integrity the sub-miniature coax assemblies work well.
>
>Bandwidths up to 28GHz.
>
>https://www.samtec.com/cables/high-speed/assemblies/qseries
>
>kw

Thanks.

I'll have a small PC board with a photodiode and a comparator, and
want to fan that diff PECL trigger pulse out to a few other boards.
Each connection is just one signal pair. I need a tiny equivalent
twinax connector.

Something sort of like this:

https://www.dropbox.com/s/hut6xlwi774tdch/T500_Ultra_1.jpg?dl=0

I guess I could use one pair in a Cat5 cable. Kinda klunky.

Regular ribbon cable is probably OK for sending a single rising edge a
couple of feet. The rest of the pulse can be arbitrarily ugly.

I should TDR a pair of PCBs with traces/connectors/cables.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Sat, 22 May 2021 17:36:43 -0700, jlarkin@highlandsniptechnology.com
wrote:

>
>
>I want to send a fast trigger pulse a short distance inside a
>rackmount enclosure, a foot or two between boards. Signals will be
>pretty fast differential PECL, maybe 120 ps edges.
>
>The usual ribbon cable config would be
>
>g g P N g g (maybe 120 ohms diff impedance)
>
>namely a differential pair with surrounding grounds.
>
>But one could also do
>
>g g P g N g g or
>g g P g g N g g (about 80 ohms per wire, 160 diff)
>
>or even
>
>g g P P g g N N g g (who knows?)
>
>
>Maybe some would have lower losses than the first one.
>
>Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
>Lemo/Fisher connectors are too expensive and fussy.

Can you do two copper layers? A common form is a crossed quad:

gggPNggg
gggNPggg

Being a quadrapole, the fields drop off quickly away from the quad.

Joe Gwinn

TI discusses LVDS over ribbon cable here:

https://www.ti.com/lit/an/slyt172/slyt172.pdf

Though they're using twisted ribbon cable.

Intel talks about LVDS over standard ribbon cable here:

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/wp/wp_lvdsboard.pdf

They use the gPNgPNg scheme that I've seen in other places, specifically Kasli/EEM:

https://github.com/sinara-hw/meta/wiki/EEM

-Jim M.

On Sun, 23 May 2021 15:08:01 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:

>On Sat, 22 May 2021 17:36:43 -0700, jlarkin@highlandsniptechnology.com
>wrote:
>
>>
>>
>>I want to send a fast trigger pulse a short distance inside a
>>rackmount enclosure, a foot or two between boards. Signals will be
>>pretty fast differential PECL, maybe 120 ps edges.
>>
>>The usual ribbon cable config would be
>>
>>g g P N g g (maybe 120 ohms diff impedance)
>>
>>namely a differential pair with surrounding grounds.
>>
>>But one could also do
>>
>>g g P g N g g or
>>g g P g g N g g (about 80 ohms per wire, 160 diff)
>>
>>or even
>>
>>g g P P g g N N g g (who knows?)
>>
>>
>>Maybe some would have lower losses than the first one.
>>
>>Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
>>Lemo/Fisher connectors are too expensive and fussy.
>
>Can you do two copper layers? A common form is a crossed quad:
>
>gggPNggg
>gggNPggg
>
>Being a quadrapole, the fields drop off quickly away from the quad.
>
>Joe Gwinn

We usually avoid stackups that have adjacent signal layers. We
alternate signal and ground/power planes to reduce crosstalk.

But I was thinking about ribbon cable signals as regards the ggPNgg
thing.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Sun, 23 May 2021 12:29:14 -0700 (PDT), Jim MacArthur
<jimbmacarthur@gmail.com> wrote:

>TI discusses LVDS over ribbon cable here:
>
>https://www.ti.com/lit/an/slyt172/slyt172.pdf
>
>Though they're using twisted ribbon cable.
>
>Intel talks about LVDS over standard ribbon cable here:
>
>https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/wp/wp_lvdsboard.pdf
>
>They use the gPNgPNg scheme that I've seen in other places, specifically Kasli/EEM:
>
>https://github.com/sinara-hw/meta/wiki/EEM
>
>-Jim M.
>
>

My pseudo-thinking was that ribbon cable pattern

ggPNgg

concentrates current in the tiny bit of dielectric between the signal
traces, which might increase both dielectric and skin losses.

ggPPggNNgg

moves more of the field into air and has more copper, so maybe less
skin loss.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Sun, 23 May 2021 11:26:57 -0700, jlarkin@highlandsniptechnology.com
wrote:

>On Sun, 23 May 2021 10:33:24 -0700 (PDT), "ke...@kjwdesigns.com"
><keith@kjwdesigns.com> wrote:
>
>>On Saturday, 22 May 2021 at 17:36:56 UTC-7, jla...@highlandsniptechnology.com wrote:
>>...
>>
>>We often use Samtec connectors and cables for similar applications.
>>
>>For high bandwidth with excellent signal integrity the sub-miniature coax assemblies work well.
>>
>>Bandwidths up to 28GHz.
>>
>>https://www.samtec.com/cables/high-speed/assemblies/qseries
>>
>>kw
>
>Thanks.
>
>I'll have a small PC board with a photodiode and a comparator, and
>want to fan that diff PECL trigger pulse out to a few other boards.
>Each connection is just one signal pair. I need a tiny equivalent
>twinax connector.
>
>Something sort of like this:
>
>https://www.dropbox.com/s/hut6xlwi774tdch/T500_Ultra_1.jpg?dl=0
>
>I guess I could use one pair in a Cat5 cable. Kinda klunky.
>
>Regular ribbon cable is probably OK for sending a single rising edge a
>couple of feet. The rest of the pulse can be arbitrarily ugly.
>
>I should TDR a pair of PCBs with traces/connectors/cables.

This looks better:

https://www.dropbox.com/s/tsbzekrln6c0imu/T500_Ultra_2.jpg?raw=1

Given an ECL part with differential inputs, why buy a comparator?

The flop resets itself, becomes a one-shot, stretching the
picoseconds-wide optical trigger. Gotta test that. Some gates hang up
if you connect an output to reset, but this should be OK. An EP gate
has a lot of gain and the RLC thing helps too.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

jla...@highlandsniptechnology.com
23.05.2021, 02:36:56 (gestern)
> I want to send a fast trigger pulse a short distance inside a
> rackmount enclosure, a foot or two between boards. Signals will be
> pretty fast differential PECL, maybe 120 ps edges.

Hello,

we do fast synchronising and triggering with LVPECL too.
0,5m is a long distance for 100ps pulses, the HP8133A delivers 60ps...

An example: Resync module under test (1 channel, 2nd version)

https://ibtk.de/project/hzdr/Resync-presentation/20180116_Resync_test_IMG_6136_1k.jpg
screenshot:
https://ibtk.de/project/hzdr/Resync-presentation/20180116_Resync_100MHz_reflections_screenshot_IMG_6138_1k_2.jpg

As can be seen clearly, a ~5cm stub (SMA-Tee, connectors, short symmetric board connections to the receiver and back) will act catastrophically on sub 100ps-edges.
So, for low phase noise we use "good" coaxials only, driven by the old but good EP89.
The first LVPECL receivers were EP11, the module in the picture used NB6L11 (unfortunately obsolete), the next version will use ADCLK925 or its derivatives.
All high speed signals are routed in front of the modules, the ribbon backplane carrys digitals and power only.
For longer distances or if the signal has to put into another cabinet, we use Fibers, consequently.

Which advantage has the -1.5V VEE?
I use a 3-resistor-termination, routed through the receiver's inputs.
https://ibtk.de/project/hzdr/Resync-presentation/20171204_resync_v2_renumber_schematic_clk-channel.png

Cheers, Timo

On Mon, 24 May 2021 02:46:27 -0700 (PDT), "timo.k...@ibtk.de"
<timo.kirschke@ibtk.de> wrote:

>jla...@highlandsniptechnology.com
>23.05.2021, 02:36:56 (gestern)
>> I want to send a fast trigger pulse a short distance inside a
>> rackmount enclosure, a foot or two between boards. Signals will be
>> pretty fast differential PECL, maybe 120 ps edges.
>
>Hello,
>
>we do fast synchronising and triggering with LVPECL too.
>0,5m is a long distance for 100ps pulses, the HP8133A delivers 60ps...
>
>An example: Resync module under test (1 channel, 2nd version)
>
>https://ibtk.de/project/hzdr/Resync-presentation/20180116_Resync_test_IMG_6136_1k.jpg
>screenshot:
>https://ibtk.de/project/hzdr/Resync-presentation/20180116_Resync_100MHz_reflections_screenshot_IMG_6138_1k_2.jpg
>
>As can be seen clearly, a ~5cm stub (SMA-Tee, connectors, short symmetric board connections to the receiver and back) will act catastrophically on sub 100ps-edges.

All I need is a single rising edge as a trigger, at kilohertz
rep-rates. It might even be better to use slower cable drivers. I need
to try this. But I think that we can maintain good signal integrity
for single-source single-load runs. The ribbon cable connectors would
be critical. I'll have to do a proto board and test it.

The ADCLK part is interesting: it looks like it has almost-full ECL
output swing, unusual for fast parts. It's enough to drive a phemt.

Some of the laser drivers make really fast edges with big swings, like
over a volt in 25 ps. They might be good line drivers.

>So, for low phase noise we use "good" coaxials only, driven by the old but good EP89.
>The first LVPECL receivers were EP11, the module in the picture used NB6L11 (unfortunately obsolete), the next version will use ADCLK925 or its derivatives.
>All high speed signals are routed in front of the modules, the ribbon backplane carrys digitals and power only.
>For longer distances or if the signal has to put into another cabinet, we use Fibers, consequently.
>
>Which advantage has the -1.5V VEE?

If I use the diff clock input as a comparator, it gives me a wider
input common-mode range. I'd still need to be concerned about the
photodiode pulling the input above 3.3. Maybe the comparator version
is safer, if a bit slower.

>I use a 3-resistor-termination, routed through the receiver's inputs.
>https://ibtk.de/project/hzdr/Resync-presentation/20171204_resync_v2_renumber_schematic_clk-channel.png
>
>Cheers, Timo

What is that NB6L110 part? It doesn't google.

We used the EPT21 and it was horrible. Slow and shocking amounts of
jitter. LVDS line receivers are cheaper and much better.

All those jumper options and esd diodes will slow things down a
little. You can do effective jumper options with surface-mount
resistors or caps whose pads disappear into wide traces if they are
not installed.

I get the feeling that not many people do this sort of picosecond
time-domain design. The telecom people just throw equalizers at
everything.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Mon, 24 May 2021 08:05:33 -0700, jlarkin@highlandsniptechnology.com
wrote:

>On Mon, 24 May 2021 02:46:27 -0700 (PDT), "timo.k...@ibtk.de"
><timo.kirschke@ibtk.de> wrote:
>
>>jla...@highlandsniptechnology.com
>>23.05.2021, 02:36:56 (gestern)
>>> I want to send a fast trigger pulse a short distance inside a
>>> rackmount enclosure, a foot or two between boards. Signals will be
>>> pretty fast differential PECL, maybe 120 ps edges.
>>
>>Hello,
>>
>>we do fast synchronising and triggering with LVPECL too.
>>0,5m is a long distance for 100ps pulses, the HP8133A delivers 60ps...
>>
>>An example: Resync module under test (1 channel, 2nd version)
>>
>>https://ibtk.de/project/hzdr/Resync-presentation/20180116_Resync_test_IMG_6136_1k.jpg
>>screenshot:
>>https://ibtk.de/project/hzdr/Resync-presentation/20180116_Resync_100MHz_reflections_screenshot_IMG_6138_1k_2.jpg
>>
>>As can be seen clearly, a ~5cm stub (SMA-Tee, connectors, short symmetric board connections to the receiver and back) will act catastrophically on sub 100ps-edges.
>
>All I need is a single rising edge as a trigger, at kilohertz
>rep-rates. It might even be better to use slower cable drivers. I need
>to try this. But I think that we can maintain good signal integrity
>for single-source single-load runs. The ribbon cable connectors would
>be critical. I'll have to do a proto board and test it.
>
>The ADCLK part is interesting: it looks like it has almost-full ECL
>output swing, unusual for fast parts. It's enough to drive a phemt.
>
>Some of the laser drivers make really fast edges with big swings, like
>over a volt in 25 ps. They might be good line drivers.
>
>
>>So, for low phase noise we use "good" coaxials only, driven by the old but good EP89.
>>The first LVPECL receivers were EP11, the module in the picture used NB6L11 (unfortunately obsolete), the next version will use ADCLK925 or its derivatives.
>>All high speed signals are routed in front of the modules, the ribbon backplane carrys digitals and power only.
>>For longer distances or if the signal has to put into another cabinet, we use Fibers, consequently.
>>
>>Which advantage has the -1.5V VEE?
>
>If I use the diff clock input as a comparator, it gives me a wider
>input common-mode range. I'd still need to be concerned about the
>photodiode pulling the input above 3.3. Maybe the comparator version
>is safer, if a bit slower.
>
>>I use a 3-resistor-termination, routed through the receiver's inputs.
>>https://ibtk.de/project/hzdr/Resync-presentation/20171204_resync_v2_renumber_schematic_clk-channel.png
>>
>>Cheers, Timo
>
>What is that NB6L110 part? It doesn't google.
>
>We used the EPT21 and it was horrible. Slow and shocking amounts of
>jitter. LVDS line receivers are cheaper and much better.

Sorry, that was the ELT21.

Still, an LVDS receiver might be better.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Sat, 22 May 2021 17:36:43 -0700, jlarkin@highlandsniptechnology.com
wrote:

>
>
>I want to send a fast trigger pulse a short distance inside a
>rackmount enclosure, a foot or two between boards. Signals will be
>pretty fast differential PECL, maybe 120 ps edges.
>
>The usual ribbon cable config would be
>
>g g P N g g (maybe 120 ohms diff impedance)
>
>namely a differential pair with surrounding grounds.
>
>But one could also do
>
>g g P g N g g or
>g g P g g N g g (about 80 ohms per wire, 160 diff)
>
>or even
>
>g g P P g g N N g g (who knows?)
>
>
>Maybe some would have lower losses than the first one.
>
>Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
>Lemo/Fisher connectors are too expensive and fussy.

Here's a comparison

https://www.dropbox.com/sh/0ulhzhsrtissnoq/AABmyLrcc42PobR0xQCorpDWa?dl=0

of ggSgg to gSSgg.

As expected from advanced electromagnetic theory/wild guessing, the
double wire thing is lower impedance and faster rise time. It's a good
model for

ggPPggNNgg

jla...@highlandsniptechnology.com schrieb am Montag, 24. Mai 2021 um 18:14:36 UTC+2:
> On Mon, 24 May 2021 08:05:33 -0700, jla...@highlandsniptechnology.com
> All I need is a single rising edge as a trigger, at kilohertz
> rep-rates. It might even be better to use slower cable drivers.

Slew rate translates into phase noise --> should be steep enough.

> The ADCLK part is interesting...

We tried it 10 years ago already with good results. See:
https://ibtk.de/project/hzdr/Resync-presentation/20110826_central_trigger_generator.pdf
The layout has to be adequate.
I am way too slow, this project delays for years...

> Maybe the comparator version is safer, if a bit slower.

We used a fast ADCMP at first in a "simple" TTL-fanout. It's trigger level and Hysteresis seemed to shift a lot with frequency as I believe to remember.
Better to use LVPECL, if possible.

> What is that NB6L110 part? It doesn't google.
NB6L11D
https://ibtk.de/project/hzdr/Resync-presentation/NB6L11-D_1-2_Fanout_Buffer_PECL_R9_20130620.PDF

> We used the EPT21 and it was horrible.
This part is a LVPECL to TTL translator. Use it for that, only for that, application.
We used it as a driver for the monoflop to visualise input pulses only.

> All those jumper options and esd diodes will slow things down a little.

The ESD protection _is_ necessary in our labs. Many people don't want to accept this, I know...
I used low-cap TVS.
The 2mm-jumpers are user-settable, for DC/AC, single-ended/differential, termination.
Soldering is too much effort. It's not optimal, but works.

For phase noise results you might have a look to Abb. 4.9 and 4.10 in comparison to 4.8:
https://ibtk.de/project/hzdr/Resync-presentation/20210305_Resyncmodul_V2_Dokumentation.pdf
This doc isn't complete in any way and in German too, sorry.

Cheers, Timo

On Tue, 25 May 2021 01:49:29 -0700 (PDT), "timo.k...@ibtk.de"
<timo.kirschke@ibtk.de> wrote:

>jla...@highlandsniptechnology.com schrieb am Montag, 24. Mai 2021 um 18:14:36 UTC+2:
>> On Mon, 24 May 2021 08:05:33 -0700, jla...@highlandsniptechnology.com
>> All I need is a single rising edge as a trigger, at kilohertz
>> rep-rates. It might even be better to use slower cable drivers.
>
>Slew rate translates into phase noise --> should be steep enough.
>
>> The ADCLK part is interesting...
>
>We tried it 10 years ago already with good results. See:
>https://ibtk.de/project/hzdr/Resync-presentation/20110826_central_trigger_generator.pdf
>The layout has to be adequate.
>I am way too slow, this project delays for years...
>
>> Maybe the comparator version is safer, if a bit slower.
>
>We used a fast ADCMP at first in a "simple" TTL-fanout. It's trigger level and Hysteresis seemed to shift a lot with frequency as I believe to remember.
>Better to use LVPECL, if possible.
>
>> What is that NB6L110 part? It doesn't google.
>NB6L11D
>https://ibtk.de/project/hzdr/Resync-presentation/NB6L11-D_1-2_Fanout_Buffer_PECL_R9_20130620.PDF
>
>> We used the EPT21 and it was horrible.
>This part is a LVPECL to TTL translator. Use it for that, only for that, application.
>We used it as a driver for the monoflop to visualise input pulses only.
>
>> All those jumper options and esd diodes will slow things down a little.
>
>The ESD protection _is_ necessary in our labs. Many people don't want to accept this, I know...
>I used low-cap TVS.
>The 2mm-jumpers are user-settable, for DC/AC, single-ended/differential, termination.
>Soldering is too much effort. It's not optimal, but works.
>
>For phase noise results you might have a look to Abb. 4.9 and 4.10 in comparison to 4.8:
>https://ibtk.de/project/hzdr/Resync-presentation/20210305_Resyncmodul_V2_Dokumentation.pdf
>This doc isn't complete in any way and in German too, sorry.
>
>Cheers, Timo

Even cmos-speed edges can have sub-ps jitter. We've got down to about
30 fs RMS jitter with fast ECL parts. I'm thinking that I can
distribute a trigger pulse over ribbon cable with below 1 ps RMS
jitter, if the local emi environment is good, which it should be
inside my box.

USB c connectors and cables might be interesting too.

On Tue, 25 May 2021 10:45:49 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

>On Tue, 25 May 2021 01:49:29 -0700 (PDT), "timo.k...@ibtk.de"
><timo.kirschke@ibtk.de> wrote:
>
>>jla...@highlandsniptechnology.com schrieb am Montag, 24. Mai 2021 um 18:14:36 UTC+2:
>>> On Mon, 24 May 2021 08:05:33 -0700, jla...@highlandsniptechnology.com
>>> All I need is a single rising edge as a trigger, at kilohertz
>>> rep-rates. It might even be better to use slower cable drivers.
>>
>>Slew rate translates into phase noise --> should be steep enough.
>>
>>> The ADCLK part is interesting...
>>
>>We tried it 10 years ago already with good results. See:
>>https://ibtk.de/project/hzdr/Resync-presentation/20110826_central_trigger_generator.pdf
>>The layout has to be adequate.
>>I am way too slow, this project delays for years...
>>
>>> Maybe the comparator version is safer, if a bit slower.
>>
>>We used a fast ADCMP at first in a "simple" TTL-fanout. It's trigger level and Hysteresis seemed to shift a lot with frequency as I believe to remember.
>>Better to use LVPECL, if possible.
>>
>>> What is that NB6L110 part? It doesn't google.
>>NB6L11D
>>https://ibtk.de/project/hzdr/Resync-presentation/NB6L11-D_1-2_Fanout_Buffer_PECL_R9_20130620.PDF
>>
>>> We used the EPT21 and it was horrible.
>>This part is a LVPECL to TTL translator. Use it for that, only for that, application.
>>We used it as a driver for the monoflop to visualise input pulses only.
>>
>>> All those jumper options and esd diodes will slow things down a little.
>>
>>The ESD protection _is_ necessary in our labs. Many people don't want to accept this, I know...
>>I used low-cap TVS.
>>The 2mm-jumpers are user-settable, for DC/AC, single-ended/differential, termination.
>>Soldering is too much effort. It's not optimal, but works.
>>
>>For phase noise results you might have a look to Abb. 4.9 and 4.10 in comparison to 4.8:
>>https://ibtk.de/project/hzdr/Resync-presentation/20210305_Resyncmodul_V2_Dokumentation.pdf
>>This doc isn't complete in any way and in German too, sorry.
>>
>>Cheers, Timo
>
>Even cmos-speed edges can have sub-ps jitter. We've got down to about
>30 fs RMS jitter with fast ECL parts. I'm thinking that I can
>distribute a trigger pulse over ribbon cable with below 1 ps RMS
>jitter, if the local emi environment is good, which it should be
>inside my box.
>
>USB c connectors and cables might be interesting too.
>
>

I think we'll use RJ45 connectors and thin CAT6 cables. One pair can
be our diff PECL trigger, and the rest can be power supplies or
something. The thin ethernet cables are nice.

On 5/22/21 5:36 PM, jlarkin@highlandsniptechnology.com wrote:
>
>
> I want to send a fast trigger pulse a short distance inside a
> rackmount enclosure, a foot or two between boards. Signals will be
> pretty fast differential PECL, maybe 120 ps edges.
>
> The usual ribbon cable config would be
>
> g g P N g g (maybe 120 ohms diff impedance)
>
> namely a differential pair with surrounding grounds.
>
> But one could also do
>
> g g P g N g g or
> g g P g g N g g (about 80 ohms per wire, 160 diff)
>
> or even
>
> g g P P g g N N g g (who knows?)
>
>
> Maybe some would have lower losses than the first one.
>
> Regular IDC ribbon cables are nice. CAT6 would be clumsy, and the
> Lemo/Fisher connectors are too expensive and fussy.
>

I have used Parlex cable for up to 5GHz and in our case that was (IIRC)
a 20ft length. Standard lengths with the ends prepared for connector
insertion go up to 27" AFAIR.

Looks like this, comes in various numbers of lines and the ends slide
into a connector that then "grips" them:

https://www.ermec.com/photogallery/2019/zif.png

This stuff seems indestructable and you could probably pull out a small
tree stump with it.

--
Regards, Joerg

http://www.analogconsultants.com/

On Tuesday, May 25, 2021 at 11:51:09 AM UTC-7, John Larkin wrote:

[about a fast edge transmission]

> I think we'll use RJ45 connectors and thin CAT6 cables. One pair can
> be our diff PECL trigger, and the rest can be power supplies or
> something. The thin ethernet cables are nice.

Thin coax is nicer. Semirigid is nicer still, if you really care about dispersion.
Twisted pairs are convenient, but those RJ45 connectors are not the greatest
transmission line terminations...
Sharing a cable with a potentially noisy power supply doesn't seem wise. There's
modulated load current on power lines.